Unpack theme data from extensions off of UI thread.

chrome/browser/themes/theme_service_browsertest.cc

Index: chrome/browser/themes/theme_service_browsertest.cc
diff --git a/chrome/browser/themes/theme_service_browsertest.cc b/chrome/browser/themes/theme_service_browsertest.cc
index 7ed174151324f3fc0573648142d81a76b9607ee3..d9d19f96631371ebe3a85bb868c564b411e90cbf 100644
--- a/chrome/browser/themes/theme_service_browsertest.cc
+++ b/chrome/browser/themes/theme_service_browsertest.cc
@@ -7,6 +7,7 @@
 #include "base/macros.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/threading/thread_restrictions.h"
+#include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/component_loader.h"
 #include "chrome/browser/extensions/extension_browsertest.h"
 #include "chrome/browser/profiles/profile.h"
@@ -15,6 +16,7 @@
 #include "chrome/browser/ui/browser.h"
 #include "chrome/common/pref_names.h"
 #include "components/prefs/pref_service.h"
+#include "content/public/test/test_utils.h"
 
 namespace {
 
@@ -59,6 +61,14 @@ IN_PROC_BROWSER_TEST_F(ThemeServiceBrowserTest, PRE_ThemeDataPackInvalid) {
             profile->GetPrefs()->GetFilePath(prefs::kCurrentThemePackFilename));
 
   InstallExtension(test_data_dir_.AppendASCII("theme"), 1);
+  // The theme isn't installed synchronously.
+  EXPECT_FALSE(UsingCustomTheme(*theme_service));
+
+  // Wait for the theme to be loaded.
+  content::WindowedNotificationObserver theme_change_observer(
+      chrome::NOTIFICATION_BROWSER_THEME_CHANGED,
+      content::Source<ThemeService>(theme_service));
+  theme_change_observer.Wait();
 
   // Check that the theme was installed.
   EXPECT_TRUE(UsingCustomTheme(*theme_service));